The present invention relates generally to filling machines and more specifically to rolling diaphragm filling units utilized on filling machines.
Filling machines in which one or more containers such as, bottles, ampules, etc. are individually or simultaneously filled by filling units from a respective nozzle to be lowered into the containers, or held above the containers are known in the art, for example, as described in Bennett U.S. Pat. No. 4,212,416. The filling units, sometimes referred to as pumps or metering units, have generally included a piston-cylinder arrangement wherein the piston rod is connected to a piston to both push and pull the piston during a reciprocal intake and discharge stroke of the filling unit.
The filling units or pumping units, generally including five major components, mainly a head, a piston, a cylinder, an inlet valve, and an outlet valve. The head has an internal chamber connecting the cylinder and inlet and outlet valves mounted at appropriate ports. Generally the head has been uniquely designed to receive specific pistons and cylinders, inlet valves and outlet valves. A more universal design is disclosed in Ruhl et al U.S. Pat. No. 5,154,589. The inlet and outlet valves are shown as check valves, spool valves, and duck-bill valves. The piston includes a standard piston with a dynamic seal as well as a rolling diaphragm pump. A further example of a rolling diaphragm pump which allows controlling the amount of material dispensed through the stroke of the diaphragm is shown in Bergandy U.S. Pat. No. 4,569,378. All three of the above patents are incorporated herein by reference.
Whereas the Ruhl, et al. U.S. Pat. No. 5,154,589 is designed for ease of assembly, there is still a need to flush the filling unit when changing materials. Pharmaceutical manufacturers are seeking to utilize disposable, instead of reusable, product contact parts in the processing equipment to eliminate the possibility of cross contamination. The early rolling diaphragm pumps of the Bergandy U.S. Pat. No. 4,569,378 have the advantage of no frictional contact parts in the material flow path, minimal particulate generation and a high degree of accuracy. Although it has been designed with reusable parts, it has not utilized disposable parts. Also, some users have cited an excessive number of working parts to assemble or disassemble the pump even for the reusable product contact parts.
When the pump is disassembled, the head and diaphragm separate from each other and therefore the contents of the working chamber between the head and the diaphragm escape. This provides a very messy situation. Also depending upon the material being dispensed, this could provide a very dangerous situation for the operator who is reconditioning the pump.
Although positive displacement piston pumps are used extensively throughout the pharmaceutical industry for fluid metering, there are considerable ongoing costs associated with these units in sterile applications. For the most part, these costs are related to disassembly, sterilization, and reassembly of the pumps at frequent intervals. When a wide variety of pump sizes are used on multiple machines, the control logistics can become quite elaborate and costly, due to the number of possible combinations of components.
Peristaltic type pumps are also used throughout the pharmaceutical industry for fluid metering. Although this type of pump offers the advantages of no frictional contact parts in the material flow path and disposable product contact parts, experience has shown that peristaltic pumps do not offer the filling accuracy and speed that is possible with rolling diaphragm pumps.
Thus, it is an object of the present invention to provide a rolling diaphragm pump with a minimal number of parts which facilitates easier assembly and disassembly.
Another object of the present invention is to provide a rolling diaphragm filling unit utilizing disposable product contact parts to eliminate the possibility of cross contamination between different products.
A further object of the present invention is to provide a rolling diaphragm filling unit utilizing disposable product contact parts that may be pre-packaged and/or pre-sterilized.
An even further object of the present invention is to provide a rolling diaphragm filling unit which is conducive to assembly, disassembly, and maintenance by inexperienced personnel.
A still further object of the present invention is to reduce the initial cost and ongoing maintenance expense of rolling diaphragm pumps to the extent that their use can extend beyond sterile filling applications into the area of general purpose fluid metering.
A still even further object of the present invention is to provide a rolling diaphragm filling unit wherein the head and rolling diaphragm are removed without the escape of any material in the working chamber.
These and other objects are achieved by combining the head, rolling diaphragm, intake and discharge ports into a single module, separate and easily removable from the principle cylinder of a rolling diaphragm filling unit.
Intake and discharge valves of various types may be mounted directly in the head, or may be mounted remote to the head module and fluidly connected directly to the head by means of tubing. The head may include separate intake and discharge ports or a single port may be used, in conjunction with a T-connector, with intake and discharge valves mounted directly or remotely to the tee on opposite sides of the port. Tapered flanges on the head module and base facilitate the clamping together of these units by a ring-type, quick-disconnect clamp. The flanges of the rolling diaphragm provide an air and liquid tight seal between the head and base. Although the rolling diaphragm is a part of the head module, it may be removably attached to the head so as to facilitate visual inspection of the product contact surfaces of the head cavity prior to fixing the diaphragm to the head and clamping the head module to the base. This may be achieved by a friction fit between a flange on the diaphragm and a recess in the head and/or by a snap-on clamp. The diaphragm may be fixedly attached to the head by an adhesive. The head module, including the porting arrangement, and the attached rolling diaphragm, comprise a disposable module which includes all of the pump surfaces that come into contact with the fluid product. The base contains a port to provide vacuum assist to ensure full convolution of the rolling diaphragm. The base, comprised of the cylinder and piston arrangement, are the permanent elements of the filling unit and are fabricated of metal, usually stainless steel, and other non-disposable type materials. The disposable head module is fabricated of plastic and/or other economical material.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.